Aside from the mayor's residence, three other houses were raided in the port city in Misamis Occidental province and resulted in the arrests of five suspects.

At least one police officer was wounded during the clashes, police said.

A woman weeps near the scene where her husband was killed in Quezon city as Duterte's crackdown on narcotics in the country continues

The drug killings have been widely criticized by Western governments and human rights groups that have called for an end to what they suspect were extrajudicial killings related to the anti-drug campaign

Another mayor suspected of involvement in illegal drugs in southern Mindanao and nine of his men were killed in a shootout at a police checkpoint in Cotabato in October.

All three mayors were among more than 160 officials Duterte named publicly as being linked to illegal drugs in August last year as part of a shame campaign.

Relatives carry the coffin of Nino Maruso, who was killed by police in what they say was a drug buy-bust operation

Duterte won the presidency last year after promising to kill tens of thousands of criminals to prevent the Philippines from becoming a narco-state

Duterte, a former mayor from the southern city of Davao, won presidential elections last May after pledging to slaughter tens of thousands of drug suspects.

He has vowed not to stop until the last drug trafficker in the country has been eliminated.

He has called on police and even civilians to kill drug users.

Duterte said he would be 'happy to slaughter' three million drug addicts, and likened his campaign to Nazi leader Adolf Hitler's efforts to exterminate Jews in Europe.

He later apologised for his Hitler reference, but said he was 'emphatic' about wanting to kill drug users.

Fisherman in the Philippines have said they have been dumping bodies of drug suspects on the orders of police, who human rights groups accuse of carrying out thousands of extra-judicial killings.

According to human rights groups, Philippine security forces and 'unidentified gunmen' have killed almost 8,000 Filipino drugs suspects, the largest number of civilian deaths in South-east Asia since the Khmer Rouge genocide in Cambodia in the 1970s.

They have accused Duterte of 'unleashing a human rights calamity' in the Philippines.

'The extraordinary brutality of the Duterte drug war is undeniable,' it said in a statement released last week.

'Many of the victims are found in back alleys or street corners wrapped in packing tape, their bodies bullet-ridden or bearing stab wounds and other signs of torture.'